1 // SPDX-License-Identifier: GPL-2.0+
3 * Voltage regulators coupler for NVIDIA Tegra20
4 * Copyright (C) 2019 GRATE-DRIVER project
6 * Voltage constraints borrowed from downstream kernel sources
7 * Copyright (C) 2010-2011 NVIDIA Corporation
10 #define pr_fmt(fmt) "tegra voltage-coupler: " fmt
12 #include <linux/init.h>
13 #include <linux/kernel.h>
15 #include <linux/reboot.h>
16 #include <linux/regulator/coupler.h>
17 #include <linux/regulator/driver.h>
18 #include <linux/regulator/machine.h>
19 #include <linux/suspend.h>
21 #include <soc/tegra/fuse.h>
22 #include <soc/tegra/pmc.h>
24 struct tegra_regulator_coupler {
25 struct regulator_coupler coupler;
26 struct regulator_dev *core_rdev;
27 struct regulator_dev *cpu_rdev;
28 struct regulator_dev *rtc_rdev;
29 struct notifier_block reboot_notifier;
30 struct notifier_block suspend_notifier;
31 int core_min_uV, cpu_min_uV;
32 bool sys_reboot_mode_req;
34 bool sys_suspend_mode_req;
35 bool sys_suspend_mode;
38 static inline struct tegra_regulator_coupler *
39 to_tegra_coupler(struct regulator_coupler *coupler)
41 return container_of(coupler, struct tegra_regulator_coupler, coupler);
44 static int tegra20_core_limit(struct tegra_regulator_coupler *tegra,
45 struct regulator_dev *core_rdev)
53 * Tegra20 SoC has critical DVFS-capable devices that are
54 * permanently-active or active at a boot time, like EMC
55 * (DRAM controller) or Display controller for example.
57 * The voltage of a CORE SoC power domain shall not be dropped below
58 * a minimum level, which is determined by device's clock rate.
59 * This means that we can't fully allow CORE voltage scaling until
60 * the state of all DVFS-critical CORE devices is synced.
62 if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) {
63 pr_info_once("voltage state synced\n");
67 if (tegra->core_min_uV > 0)
68 return tegra->core_min_uV;
70 core_cur_uV = regulator_get_voltage_rdev(core_rdev);
74 core_max_uV = max(core_cur_uV, 1200000);
76 err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
81 * Limit minimum CORE voltage to a value left from bootloader or,
82 * if it's unreasonably low value, to the most common 1.2v or to
83 * whatever maximum value defined via board's device-tree.
85 tegra->core_min_uV = core_max_uV;
87 pr_info("core voltage initialized to %duV\n", tegra->core_min_uV);
89 return tegra->core_min_uV;
92 static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev,
93 struct regulator_dev *rtc_rdev)
95 struct coupling_desc *c_desc = &core_rdev->coupling_desc;
96 struct regulator_dev *rdev;
100 for (i = 1; i < c_desc->n_coupled; i++) {
101 max_spread = core_rdev->constraints->max_spread[i - 1];
102 rdev = c_desc->coupled_rdevs[i];
104 if (rdev == rtc_rdev && max_spread)
108 pr_err_once("rtc-core max-spread is undefined in device-tree\n");
113 static int tegra20_cpu_nominal_uV(void)
115 switch (tegra_sku_info.soc_speedo_id) {
125 static int tegra20_core_nominal_uV(void)
127 switch (tegra_sku_info.soc_speedo_id) {
135 static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra,
136 struct regulator_dev *core_rdev,
137 struct regulator_dev *rtc_rdev,
138 int cpu_uV, int cpu_min_uV)
140 int core_min_uV, core_max_uV = INT_MAX;
141 int rtc_min_uV, rtc_max_uV = INT_MAX;
150 * RTC and CORE voltages should be no more than 170mV from each other,
151 * CPU should be below RTC and CORE by at least 120mV. This applies
152 * to all Tegra20 SoC's.
154 max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev);
157 * The core voltage scaling is currently not hooked up in drivers,
158 * hence we will limit the minimum core voltage to a reasonable value.
159 * This should be good enough for the time being.
161 core_min_uV = tegra20_core_limit(tegra, core_rdev);
165 err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV);
169 err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV,
174 /* prepare voltage level for suspend */
175 if (tegra->sys_suspend_mode)
176 core_min_uV = clamp(tegra20_core_nominal_uV(),
177 core_min_uV, core_max_uV);
179 core_uV = regulator_get_voltage_rdev(core_rdev);
183 core_min_uV = max(cpu_min_uV + 125000, core_min_uV);
184 if (core_min_uV > core_max_uV)
187 if (cpu_uV + 120000 > core_uV)
188 pr_err("core-cpu voltage constraint violated: %d %d\n",
189 core_uV, cpu_uV + 120000);
191 rtc_uV = regulator_get_voltage_rdev(rtc_rdev);
195 if (cpu_uV + 120000 > rtc_uV)
196 pr_err("rtc-cpu voltage constraint violated: %d %d\n",
197 rtc_uV, cpu_uV + 120000);
199 if (abs(core_uV - rtc_uV) > 170000)
200 pr_err("core-rtc voltage constraint violated: %d %d\n",
203 rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread);
205 err = regulator_check_voltage(rtc_rdev, &rtc_min_uV, &rtc_max_uV);
209 while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) {
210 if (core_uV < core_min_uV) {
211 core_target_uV = min(core_uV + max_spread, core_min_uV);
212 core_target_uV = min(rtc_uV + max_spread, core_target_uV);
214 core_target_uV = max(core_uV - max_spread, core_min_uV);
215 core_target_uV = max(rtc_uV - max_spread, core_target_uV);
218 if (core_uV == core_target_uV)
221 err = regulator_set_voltage_rdev(core_rdev,
228 core_uV = core_target_uV;
230 if (rtc_uV < rtc_min_uV) {
231 rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV);
232 rtc_target_uV = min(core_uV + max_spread, rtc_target_uV);
234 rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV);
235 rtc_target_uV = max(core_uV - max_spread, rtc_target_uV);
238 if (rtc_uV == rtc_target_uV)
241 err = regulator_set_voltage_rdev(rtc_rdev,
248 rtc_uV = rtc_target_uV;
254 static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra,
255 struct regulator_dev *cpu_rdev,
256 struct regulator_dev *core_rdev,
257 struct regulator_dev *rtc_rdev)
261 cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
265 return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
269 static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra,
270 struct regulator_dev *cpu_rdev,
271 struct regulator_dev *core_rdev,
272 struct regulator_dev *rtc_rdev)
274 int cpu_min_uV_consumers = 0;
275 int cpu_max_uV = INT_MAX;
280 err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV);
284 err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV,
289 err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers,
290 &cpu_max_uV, PM_SUSPEND_ON);
294 cpu_uV = regulator_get_voltage_rdev(cpu_rdev);
298 /* store boot voltage level */
299 if (!tegra->cpu_min_uV)
300 tegra->cpu_min_uV = cpu_uV;
303 * CPU's regulator may not have any consumers, hence the voltage
304 * must not be changed in that case because CPU simply won't
305 * survive the voltage drop if it's running on a higher frequency.
307 if (!cpu_min_uV_consumers)
310 /* restore boot voltage level */
311 if (tegra->sys_reboot_mode)
312 cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV);
314 /* prepare voltage level for suspend */
315 if (tegra->sys_suspend_mode)
316 cpu_min_uV = clamp(tegra20_cpu_nominal_uV(),
317 cpu_min_uV, cpu_max_uV);
319 if (cpu_min_uV > cpu_uV) {
320 err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
325 err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
326 cpu_max_uV, PM_SUSPEND_ON);
329 } else if (cpu_min_uV < cpu_uV) {
330 err = regulator_set_voltage_rdev(cpu_rdev, cpu_min_uV,
331 cpu_max_uV, PM_SUSPEND_ON);
335 err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev,
344 static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler,
345 struct regulator_dev *rdev,
346 suspend_state_t state)
348 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
349 struct regulator_dev *core_rdev = tegra->core_rdev;
350 struct regulator_dev *cpu_rdev = tegra->cpu_rdev;
351 struct regulator_dev *rtc_rdev = tegra->rtc_rdev;
353 if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) ||
354 state != PM_SUSPEND_ON) {
355 pr_err("regulators are not coupled properly\n");
359 tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req);
360 tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req);
362 if (rdev == cpu_rdev)
363 return tegra20_cpu_voltage_update(tegra, cpu_rdev,
364 core_rdev, rtc_rdev);
366 if (rdev == core_rdev)
367 return tegra20_core_voltage_update(tegra, cpu_rdev,
368 core_rdev, rtc_rdev);
370 pr_err("changing %s voltage not permitted\n", rdev_get_name(rtc_rdev));
375 static int tegra20_regulator_prepare_suspend(struct tegra_regulator_coupler *tegra,
376 bool sys_suspend_mode)
380 if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
384 * All power domains are enabled early during resume from suspend
385 * by GENPD core. Domains like VENC may require a higher voltage
386 * when enabled during resume from suspend. This also prepares
387 * hardware for resuming from LP0.
390 WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode);
392 err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
396 err = regulator_sync_voltage_rdev(tegra->core_rdev);
403 static int tegra20_regulator_suspend(struct notifier_block *notifier,
404 unsigned long mode, void *arg)
406 struct tegra_regulator_coupler *tegra;
409 tegra = container_of(notifier, struct tegra_regulator_coupler,
413 case PM_HIBERNATION_PREPARE:
414 case PM_RESTORE_PREPARE:
415 case PM_SUSPEND_PREPARE:
416 ret = tegra20_regulator_prepare_suspend(tegra, true);
419 case PM_POST_HIBERNATION:
420 case PM_POST_RESTORE:
421 case PM_POST_SUSPEND:
422 ret = tegra20_regulator_prepare_suspend(tegra, false);
427 pr_err("failed to prepare regulators: %d\n", ret);
429 return notifier_from_errno(ret);
432 static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra,
433 bool sys_reboot_mode)
437 if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev)
440 WRITE_ONCE(tegra->sys_reboot_mode_req, true);
443 * Some devices use CPU soft-reboot method and in this case we
444 * should ensure that voltages are sane for the reboot by restoring
445 * the minimum boot levels.
447 err = regulator_sync_voltage_rdev(tegra->cpu_rdev);
451 err = regulator_sync_voltage_rdev(tegra->core_rdev);
455 WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode);
460 static int tegra20_regulator_reboot(struct notifier_block *notifier,
461 unsigned long event, void *cmd)
463 struct tegra_regulator_coupler *tegra;
466 if (event != SYS_RESTART)
469 tegra = container_of(notifier, struct tegra_regulator_coupler,
472 ret = tegra20_regulator_prepare_reboot(tegra, true);
474 return notifier_from_errno(ret);
477 static int tegra20_regulator_attach(struct regulator_coupler *coupler,
478 struct regulator_dev *rdev)
480 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
481 struct device_node *np = rdev->dev.of_node;
483 if (of_property_read_bool(np, "nvidia,tegra-core-regulator") &&
485 tegra->core_rdev = rdev;
489 if (of_property_read_bool(np, "nvidia,tegra-rtc-regulator") &&
491 tegra->rtc_rdev = rdev;
495 if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") &&
497 tegra->cpu_rdev = rdev;
504 static int tegra20_regulator_detach(struct regulator_coupler *coupler,
505 struct regulator_dev *rdev)
507 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler);
510 * We don't expect regulators to be decoupled during reboot,
511 * this may race with the reboot handler and shouldn't ever
512 * happen in practice.
514 if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING))
517 if (tegra->core_rdev == rdev) {
518 tegra->core_rdev = NULL;
522 if (tegra->rtc_rdev == rdev) {
523 tegra->rtc_rdev = NULL;
527 if (tegra->cpu_rdev == rdev) {
528 tegra->cpu_rdev = NULL;
535 static struct tegra_regulator_coupler tegra20_coupler = {
537 .attach_regulator = tegra20_regulator_attach,
538 .detach_regulator = tegra20_regulator_detach,
539 .balance_voltage = tegra20_regulator_balance_voltage,
541 .reboot_notifier.notifier_call = tegra20_regulator_reboot,
542 .suspend_notifier.notifier_call = tegra20_regulator_suspend,
545 static int __init tegra_regulator_coupler_init(void)
549 if (!of_machine_is_compatible("nvidia,tegra20"))
552 err = register_reboot_notifier(&tegra20_coupler.reboot_notifier);
555 err = register_pm_notifier(&tegra20_coupler.suspend_notifier);
558 return regulator_coupler_register(&tegra20_coupler.coupler);
560 arch_initcall(tegra_regulator_coupler_init);